After voters in South Carolina rejected four women running as Democratic Party nominees in the 2012 congressional elections, the state in a special election this May again has a chance to elect its first female House members since 1990. The likely continuation of an all-male delegation provides lessons for what it will take to achieve gender parity in Congress: a combination of gender-conscious party rules and fair voting methods.

In December, Gov. Nikki Haley appointed fellow Republican Tim Scott to the U.S. Senate to fill the vacancy created by Jim DeMint's sudden retirement. The appointment resulted in the Senate's first African American Senator in nearly two years and created a vacancy in the state's 1st congressional district.

The resulting special election has drawn particular attention because Democrats have nominated Elizabeth Colbert Busch, sister of Comedy Central's Stephen Colbert. After easily winning the Democratic primary with 96% of the vote, Colbert Busch will face the winner of a Republican primary runoff in which the favorite is former Gov. Mark Sanford, who is seeking a political comeback four years after his much-publicized extramarital affair.

Even though polls suggest a very close race, Busch faces a tough challenge in the general election in a state without a single woman in its national delegation and heavy Republican partisanship. In 2012, Mitt Romney won the 1st congressional district by 18 percentage points. With few voters today splitting their ticket in presidential and congressional elections, South Carolina's Republican House candidates have a huge advantage.

Even with Nikki Haley as governor, South Carolina has one of the nation's worse records for electing female candidates. It has never elected a woman to the U.S. Senate and only five women have been elected to the U.S. House, four of which were elected in special elections to fill vacancies caused by the deaths of their husbands.

Gov. Haley is South Carolina's only female statewide elective executive; and only three other women have filled statewide positions in the past: Nancy Stevenson was lieutenant governor (1979-1983), while Barbara Nielsen and Inez Tenenbaum were superintendents of education (Nielsen from 1991-1999, and Tenenbaum from 1999-2007).

Before ascending to 49th place in 2012, South Carolina had the lowest percentage of women in its legislature for a decade. In 2012, Republican Katrina Shealy broke through the state's all-male Senate. She was the first woman in four years to be elected to the institution, which has never held more than three women at a time, accounting for a mere 6% of the chamber.

Women have a hard time winning general elections in South Carolina, but it's not due to a lack of running on the Democratic side. While Republicans did not nominate a single female candidate for a House race in 2012 - and last did so in 2008 - four of the six Democratic nominees were women. But they all lost, by an average of nearly 20% with the biggest factor being that Romney defeated Obama in each of their districts by at least 10%. In the 1st congressional district, for example, Tim Scott defeated Bobbie Rose by 27%.

Due to winner-takes-all electoral rules, Democratic House candidates have a good chance to win just one South Carolina district, the 6th district, which has been represented for two decades by James Clyburn. Of the state's seven districts, six are controlled by Republicans with an underlying Republican partisanship of more than 57%. To put that in perspective, even while 2012 was a good year for Democrats nationally, they did not take over a single Republican seat in a district with a partisanship above 54% Republican.

The fact that Democratic women are running and losing in South Carolina underscores the misleading notion that women will always increase their representation simply by running for office. It's not only about women running; it's also about parties running women where they have a real chance to win.

Two reforms would boost representation of women in South Carolina by addressing that problem directly. First, within the current districts, few women will win without Republicans nominating more women. The 2010 gubernatorial primary provides a great example of how intervention can make a difference. In March 2010, Nikki Haley was polling at 12%, in fourth place. Two months later, she surged to the lead with 30%, and ultimately won 49% in the June primary with a landslide win of 65% to 35% in a runoff.

The May poll came four days after Haley earned the endorsement of former Alaska governor Sarah Palin. Then at the peak of her popularity, Gov. Palin that year endorsed four Republican women in competitive gubernatorial primaries who were ultimately elected. Gov. Palin may stir controversy, but her role in boosting election of women governors cannot be denied - which helps explain why today four Republican governors are women, compared to only one Democratic governor.

South Carolina Republicans have the power to adopt gender-conscious rules to enhance women's representation. At a minimum, they should create incentives for local party arms to recruit and train more women candidates. For example, South Carolina's 7th district has a strongly Republican partisanship and was the state's only open House seat in 2012. Republicans could have recruited qualified, female, primary candidates, but men won 95% of the primary vote. This year's special election in the 1st congressional district was even more abysmal; 15 of 16 Republican primary candidates were male and together won more than 99% of the vote.

Parties can go further by considering rules that parties recruit a minimum number of women candidates to run in open seat elections. Before assuming that such requirements would never gain support, consider that both the Democratic National Committee (DNC) and Republican National Committee (RNC) have party rules promoting gender parity in selection of party leaders. The RNC, for example, reserves one position for a man and one for a woman from every state and territory and requires women to hold key executive positions.

But suppose South Carolina Republicans cling to gender-blind rules and continue to almost never nominate women for high office. What else can be done?

For Democrats to win in South Carolina, they need fairer methods of voting. It's not like the state doesn't have Democratic voters - Barack Obama won more than 44% of the vote in both 2008 and 2012; and Democratic candidates for the House won 41.2% of the vote in 2012.* But the state has an unfair winner-take-all voting system that gives Democrats a realistic chance to win only one of seven districts.

Switching to a fair voting electoral system, like our proposed map with multi-seat districts and a non-winner-take-all voting system like choice voting, would allow far more voters to elect a preferred candidate. Our plan would make it easier for Republicans to have party rules that result in more women nominees and mean that Democrats would likely win three of seven seats - making the fact that Democrats nominate more women directly meaningful for changing representation.

It's premature to write off Colbert Bush this year, of course. In special elections, voter turnout can be a big wildcard, and Mark Sanford's controversial history could make him a vulnerable candidate if he wins the nomination. Also, the "Colbert bump" due to her brother's celebrity may play a meaningful role in the race.

But in today's hyper-partisan political environment, partisanship typically trumps everything else, whether it be a candidate's personal charisma, political philosophy or campaign spending. And regardless, South Carolina will remain a troubling testament of how winner-takes-all districts and a lack of gender-conscious party rules are the leading reasons for why the United States ranks 92nd in the world for representation of women in its national legislature. It's time for real change. We need to adopt gender-conscious party rules and a fair voting system.

*Two races were uncontested, the 2nd district with a Republican incumbent and the 6th district with a Democratic incumbent.